This invention relates to an ink jet recording apparatus having a plurality of ink jet printing heads moving in the width direction of a recording paper for jetting ink of different colors to the recording paper in order to print color image, the ink jet printing heads being mounted on a single carriage for enabling printing at a high density, and more particularly to a management technique appropriate for such a recording apparatus.
A recording apparatus having ink jet printing heads produces comparatively little noise during printing and can form small dots at a high density. Accordingly, such an apparatus is used for various types of color printing.
Since the recording apparatus jets ink, which is pressurized in a pressure generation chamber to recording paper as ink drops from nozzles for forming dots, it is necessary to prevent the ink from running on the recording paper in order to improve the print quality. The percentage of an ink solvent is made as small as possible and a material that is easily evaporated is used.
Since, an ink solvent is evaporated from the nozzle openings during printing, ink viscosity rises. If the nozzle face is sealed with a cap the ink viscosity in the nozzle openings still rises, and therefore jetting of ink is hindered.
To solve such a problem, a printing head is moved to an ink receptacle provided in a non-print area and ink is jetted from all nozzle openings at the expiration of a predetermined time interval during printing, for example, as disclosed in Japanese Patent Application Laid-Open No. Sho. 64-40342.
Since graphics processing can be executed comparatively easily as personal computers have developed, a printer that can output a hard copy of a color image displayed on a display is required. An ink jet printer that can execute color printing comprises a printing head for black printing and a printing head for color printing both mounted on a carriage taking into account the ink consumption amount difference and the recording density difference between colors and prevention of mixing colors at a stop time.
Although such an ink jet printer can execute text printing and color graphics printing on the same page, the user might want to use the ink jet printer to execute only monochrome printing in black ink for a long time or to execute only color printing in cyan, magenta, and yellow color inks for a long time.
In such a case, since the other printing head not involved in printing, for example, the color printing head during text printing, does not jet ink drops, ink dries in the nozzle openings in an extremely short time, clogging the nozzle openings.
To solve such a problem, normally, upon the expiration of a predetermined time interval, the printing head not involved in the print operation is moved to a non-print area and is made to an perform idle jetting operation jetting ink drops from the nozzle openings for in order to prevent dried ink from clogging the nozzle openings.
However, when ink used with one printing head differs from ink used with the other in an ink drying degree, even if one printing head is executing printing, idle jetting for the other must be performed. As a result, the printing speed is lowered and ink for the other printing head not involved in printing is consumed by the idle jetting.